Altered lipid profile, lipoprotein composition, and oxidant and antioxidant status in pediatric Crohn disease.

BACKGROUND: Growing evidence supports a role for peroxidation in the pathogenesis of Crohn disease (CD). The activation of inflammatory cells, the release of their mediators, and the excessive production of free radicals may affect circulating lipids. OBJECTIVE: We examined the lipid profile, lipoprotein composition, and oxidant-antioxidant status of children with CD. DESIGN: We studied 22 pediatric CD patients and 10 healthy control subjects. RESULTS: The proportion of saturated and monounsaturated fatty acids in plasma of CD patients was higher but that of polyunsaturated fatty acids was lower than in control subjects. This resulted in higher ratios in CD patients of palmitoleic acid to linoleic acid (P < 0. 05) and of eicosatrienoic acid to arachidonic acid (P < 0.04), 2 established indexes of essential fatty acid deficiency. Hypocholesterolemia was noted in CD patients as a result of lower LDL-cholesterol concentrations than in control subjects (P < 0.02). Plasma apolipoproteins B (P < 0.02) and A-I (P < 0.02) were also lower in CD patients, whereas plasma triacylglycerols were higher (P < 0.005). Lipoprotein composition was altered in CD patients, with relative triacylglycerol depletion and protein enrichment in VLDL. In contrast, intermediate-density lipoprotein of CD patients was characterized by an increased percentage of triacylglycerol and protein (P < 0.005) and a reduced proportion of phospholipids (P < 0. 01). Additional abnormalities were observed in the chemical distribution of HDL(2) and HDL(3) moieties. Lipid peroxidation was documented by higher plasma malondialdehyde concentrations in CD patients (P < 0.05), accompanied by lower retinol concentrations (P < 0.02). CONCLUSION: Disturbances in the lipid profile, in lipoprotein concentrations and composition, and in oxidant-antioxidant status occur in CD patients.

Acute effects of inhaled urban particles and ozone: lung morphology, macrophage activity, and plasma endothelin-1.

We studied acute responses of rat lungs to inhalation of urban particulate matter and ozone. Exposure to particles (40 mg/m3 for 4 hours; mass median aerodynamic diameter, 4 to 5 microm; Ottawa urban dust, EHC-93), followed by 20 hours in clean air, did not result in acute lung injury. Nevertheless, inhalation of particles resulted in decreased production of nitric oxide (nitrite) and elevated secretion of macrophage inflammatory protein-2 from lung lavage cells. Inhalation of ozone (0.8 parts per million for 4 hours) resulted in increased neutrophils and protein in lung lavage fluid. Ozone alone also decreased phagocytosis and nitric oxide production and stimulated endothelin-1 secretion by lung lavage cells but did not modify secretion of macrophage inflammatory protein-2. Co-exposure to particles potentiated the ozone-induced septal cellularity in the central acinus but without measurable exacerbation of the ozone-related alveolar neutrophilia and permeability to protein detected by lung lavage. The enhanced septal thickening was associated with elevated production of both macrophage inflammatory protein-2 and endothelin-1 by lung lavage cells. Interestingly, inhalation of urban particulate matter increased the plasma levels of endothelin-1, but this response was not influenced by the synergistic effects of ozone and particles on centriacinar septal tissue changes. This suggests an impact of the distally distributed particulate dose on capillary endothelial production or filtration of the vasoconstrictor. Overall, equivalent patterns of effects were observed after a single exposure or three consecutive daily exposures to the pollutants. The experimental data are consistent with epidemiological evidence for acute pulmonary effects of ozone and respirable particulate matter and suggest a possible mechanism whereby cardiovascular effects may be induced by particle exposure. In a broad sense, acute biological effects of respirable particulate matter from ambient air appear related to paracrine/endocrine disruption mechanisms.

Acute pulmonary toxicity of urban particulate matter and ozone.

We have investigated the acute lung toxicity of urban particulate matter in interaction with ozone. Rats were exposed for 4 hours to clean air, ozone (0.8 ppm), the urban dust EHC-93 (5 mg/m3 or 50 mg/m3), or ozone in combination with urban dust. The animals were returned to clean air for 32 hours and then injected (intraperitoneally) with [3H]thymidine to label proliferating cells and killed after 90 minutes. The lungs were fixed by inflation, embedded in glycol methacrylate, and processed for light microscopy autoradiography. Cell labeling was low in bronchioles (0.14 +/- 0.04%) and parenchyma (0.13 +/- 0.02%) of air control animals. Inhalation of EHC-93 alone did not induce cell labeling. Ozone alone increased (P < 0.05) cell labeling (bronchioles, 0.42 +/- 0.16%; parenchyma, 0.57 +/- 0.21%), in line with an acute reparative cell proliferation. The effects of ozone were clearly potentiated by co-exposure with either the low (3.31 +/- 0.31%; 0.99 +/- 0.18%) or the high (4.45 +/- 0.51%; 1.47 +/- 0.18%) concentrations of urban dust (ozone X EHC-93, P < 0.05). Cellular changes were most notable in the epithelia of terminal bronchioles and alveolar ducts and did not distribute to the distal parenchyma. Enhanced DNA synthesis indicates that particulate matter from ambient air can exacerbate epithelial lesions in the lungs. This may extend beyond air pollutant interactions, such as to effects of inhaled particles in the lungs of compromised individuals.

Regulation of promoter-CAT stress genes in HepG2 cells by suspensions of particles from ambient air.

A panel of HepG2-derived cell lines (CAT-Tox [L] assay, Xenometrix), harboring stress genes consisting of a sequence for chloramphenicol acetyltransferase (CAT) under the transcriptional regulation from mammalian promoters and response elements, was exposed for 18-24 hr to aqueous suspensions of urban dusts (SRM-1648, SRM-1649, EHC-93) or PM2.5 particles (particulate matter < 2.5 micron). Expression of CAT protein was measured by enzyme-linked immunosorbent assay. Induction of the CAT genes was verified with benzo[a]pyrene (CYP1A1, cytochrome P450 1A1 promoter; GSTYa, glutathione transferase subunit Ya promoter; XRE, xenobiotic response element), cadmium sulfate, and copper sulfate (HMTIIa, metallothionein IIa promoter; HSP70, heat shock protein 70 promoter). The urban dust suspensions were active on CYP1A1, GSTYa, and XRE cell lines. SRM-1648 and SRM-1649 were twice as potent as EHC-93 per unit mass in inducing the xenobiotic-dependent responses, which correlated with contents in polycyclic aromatic hydrocarbons. These three reference particles, as well as six PM2.5 preparations collected on hi-vol filters in the Great Lakes basin, were also found to induce HMTIIa and HSP70, the magnitude of the responses correlating closely with the amount of soluble copper in the particulate preparations. The results indicate that bioavailable chemical species in the unfractionated particles can directly and quantitatively induce xenobiotic, metal, and stress-dependent responses in a target cell model, resulting in patterns of gene induction consistent with the chemical compositions of the environmental materials. We propose that cell culture models could be helpful for toxicodynamic inferences in adjunct to environmental monitoring and exposure assessments.

Assessment of the role of glutathione conjugation in the protection afforded by anethol dithiolthione against hexachloro-1,3-butadiene-induced nephrotoxicity.

Administration of anethol dithiolthione (ADT) to rodents can afford protection against some chemically induced toxicities. The aim of the present study was to assess the effects of ADT on hexachloro-1,3-butadiene (HCBD)-induced nephrotoxicity in the rat and to determine the mechanism of its action. Renal integrity was evaluated by measuring urinary excretion of glucose, protein, and gamma-glutamyl transpeptidase and by histological evaluation. A 3-day pretreatment with ADT (300 mg/kg/day) protected against the toxicity of various doses of HCBD (ranging from 15.6 to 62.5 mg/kg). The pretreatment increased (1.4-fold) the nonprotein sulfhydryl content (NPSH) of the liver. However, it did not modify the biliary excretion of radiolabeled materials in [14C]HCBD- treated (20 mg/kg) rats, nor that of the bioactivated HCBD metabolite, S-(1,2,3,4,4-pentachloro-1,3-butadienyl)-glutathione (PCBG). Moreover, ADT pretreatment protected rats against the nephrotoxicity induced by PCBG (20 mg/kg) itself. The extent of covalent binding to kidney proteins of [14C]HCBD-derived metabolites was not modified by pretreatment with ADT. Incubation of rat kidney cortical slices in a medium containing 0.1 mM of the nephrotoxic glutathione (PCBG) or cysteine (PCBC, S-(1,2,3,4,4-pentachloro-1,3-butadienyl)-L-cysteine) conjugates of HCBD for 30 min resulted in a 75% reduction in the slice/medium ratio of p-aminohipurate (PAH) compared to that seen in controls. When the cortical slices were incubated with ADT (30 min, 0.2 mM) prior to incubation with the nephrotoxic conjugates, the reduction was only 33%. Neither the in vitro nor the in vivo treatments did modify the activity of renal cytosolic beta-lyase; however, the latter treatment caused an increase in NPSH content. A 15-min incubation of kidney cortical slices with glutathione (10 mM) resulted in a 5-fold increase of NPSH, but failed to prevent the reduction in PAH uptake caused by PCBG and PCBC. Altogether, the in vivo and renal slice data suggest that ADT protects rats against HCBD-induced nephrotoxicity by a mechanism that does not involve the modulation of HCBD conjugation with liver GSH, nor the modulation of the kidney NPSH level and beta-lyase activity. The mechanism of protection conferred to rats by an ADT pretreatment against HCBD-induced nephrotoxicity appears to take place in the kidney at a step beyond the generation of ultimate toxic metabolites derived from PCBC.

Distinct patterns of cow's milk allergy in infancy defined by prolonged, two-stage double-blind, placebo-controlled food challenges.

BACKGROUND: The clinical manifestations of cow's milk allergy (CMA) are highly variable, and challenges usually identify only immediate, IgE mediated reactions. OBJECTIVE: To clearly identify CMA of immediate and delayed types using a two-stage, double-blind, placebo-controlled food challenge (DBPCFC), and to prospectively compare the clinical history and analyses of specific IgE antibodies to milk in predicting outcome of DBPCFC. METHODS: A total of 69 patients (33 girls, 36 boys) were recruited for study based on a history highly suggestive of CMA and resolution of symptoms on a bovine protein-free diet. After skin-prick tests (SPTs) and search for allergen-specific serum IgE antibodies by enzyme allergosorbent test (EAST), a two-stage DBPCFC was performed over several days. RESULTS: Of 16 patients (mean age 36.9 months) classified as probable immediate reactors based on the history, 10 (62.5%) had a positive DBPCFC with similar patterns to historical adverse reactions (< or = 2 h after milk exposure). The other 53 (77%) patients (17.3 months) had a history of probable delayed type CMA presenting with predominantly gastrointestimal symptoms from 2 h and up to 6 days after milk exposure. Of these, 15 (28.8%) had a positive DBPCFC, again with a symptom pattern similar to the history. Sensitivity/specificity of SPT was similar to that of EAST for both immediate (70/83% and 62/83% respectively, NS) or delayed (0/97% and 0/97%) CMA confirmed by DBPCFC. CONCLUSIONS: Using our two-stage, prolonged DBPCFC, we clearly identified two groups of children with CMA, reflecting different pathogenesis of either immediate-type IgE-dependent, or delayed-type IgE-independent allergy. Although useful in immediate reactors, IgE antibody determination cannot predict the outcome of DBPCFC in delayed reactors. A thorough clinical history was the most helpful tool to predict the type of response in challenge positive patients.

Male rat specific nephrotoxicity resulting from subchronic administration of hexachlorobenzene.

Male rats are more sensitive to the nephrocarcinogenic effect of hexachlorobenzene (HCB) than are female rats. The purpose of this study was to shed light on this phenomenon by investigating mechanisms of subchronic nephrotoxicity of HCB. Groups of rats were administered HCB in corn oil (po) at 100 mg/kg, 5 days per week for 15 days or at 50 mg/kg, 5 days per week for 50 days. Urine was collected on Days 1, 8, and 15 for the 15-day treatment and on Day 50 for the 50-day treatment. Glucosuria, proteinuria, and enzymuria (gamma-glutamyl transpeptidase) were measured to assess renal function. Twenty-four hours after the last HCB treatment, the animals were killed and kidneys were removed for histopathological evaluation. Urine analyses showed no indication of renal dysfunction in treated animals compared to controls during the 15-day treatment. However, histology of male rat kidneys revealed degenerative and regenerative cellular foci accompanied by an increased accumulation of protein droplets in epithelial cells of the proximal tubules. The same histological observations were also made in male rats after a 50-day HCB treatment but this time they were accompanied by renal function alterations. In female rats, no such renal functional or histological alterations were observed. The histopathological observations in male rats correspond well with the protein droplet nephropathy; the latter is characteristic of the accumulation in kidney cells of alpha 2u-globulin probably caused by the reversible binding of a chemical to alpha 2u that renders the protein indigestible to kidney proteases. alpha 2u-Globulin was measured in the cytosol of male rats and was found to be increased 11-fold compared to controls. Also, HCB was found to be bound reversibly to alpha 2u. These results suggest that HCB induces a male rat specific nephropathy that could explain the higher incidence of kidney tumors in male rats compared to female rats.

Chronic intermittent elemental diet improves growth failure in children with Crohn's disease.

Growth failure often complicates Crohn's disease in pediatric patients and is principally due to inadequate caloric intake. To assess whether intermittent courses of an elemental diet could reestablish growth, 8 children (aged 9.8-14.2 yr) with Crohn's disease and growth failure entered into a prospective trial. Each patient was studied during an observation year on standard therapy, then for an experimental year during which they received enteral elemental diet 1 out of 4 mo. An age- and disease-matched control group of 4 patients was treated by conventional medical therapy during both years. Elemental diet therapy was administered nocturnally, at home, by continuous nasogastric infusion and increased the daily caloric intake by 25% (p less than 0.01). Anthropometric measurements demonstrated significant height and weight gains in the elemental diet group vs. controls (p less than 0.01). Crohn's disease activity index and prednisone intake decreased significantly in patients receiving elemental diet therapy when compared with themselves and with controls on conventional medical therapy (p less than 0.05). In contrast, the rate of pubertal development was similar in both groups irrespective of the treatment modality. This study demonstrates that chronic intermittent elemental diet effectively reverses growth arrest, while decreasing prednisone requirements and Crohn's disease activity index in pediatric Crohn's disease patients prior to puberty.