Increased gastrointestinal permeability and gut inflammation in children with functional abdominal pain and irritable bowel syndrome

Cow's-milk allergy is a risk factor for the development of FGIDs in children

OBJECTIVES

Functional gastrointestinal disorders (FGIDs) are common in children. Their pathogenesis remains unknown and is most likely multifactorial. We hypothesized that noninfectious causes of inflammation affecting the gastrointestinal (GI) tract early in life, such as cow's-milk allergy (CMA), can predispose to the development of FGIDs later in childhood.

PATIENTS AND METHODS

Case-control study. Subjects were patients between 4 and 18 years diagnosed with CMA in the first year of life at Children's Memorial Hospital in Chicago, IL, between January 2000 and June 2009. Diagnosis of CMA was based on history and clinical findings. Siblings 4 to 18 years of age without a history of CMA were selected as controls. Cases completed the parental form of the Pediatric Gastrointestinal Symptoms Rome III version questionnaire to assess for GI symptoms.

RESULTS

Fifty-two subjects (mean age 8.1 ± 4.48 years, 62% girls) and 53 controls (mean age 9.7 ± 4.20 years, 55% girls) participated in the study. Twenty-three of 52 subjects (44.2%) reported GI symptoms that included abdominal pain, constipation, or diarrhea compared with 11 of 53 controls (20.75%) (odds ratio 3.03, P = 0.01). Abdominal pain was significantly more common in cases (16/52, 30.8%) versus controls (5/53, 9.43%) (odds ratio 4.27 [1.43-12.7]) (χ² = 7.47, P = 0.01). Abnormal stool habits were more common in cases (15/52, 28.8%) versus controls (7/53, 13.2%), but the difference was not statistically significant. Ten of 52 subjects (19.2%) met the Questionnaire on Pediatric Gastrointestinal Symptoms Rome III version criteria for diagnosis of an FGID (7 irritable bowel syndrome, 2 functional dyspepsia, 1 functional abdominal pain), whereas none in the control group did.

CONCLUSIONS

CMA constitutes a risk factor for the development of FGIDs in children.

The interpretation of Rome III criteria and method of assessment affect the irritable bowel syndrome classification of children

BACKGROUND

Paediatric classification of irritable bowel syndrome (IBS) is complicated by the potential discrepancy between parent and child report and by the interpretation of pain-stool relations in the Rome III classification system.

AIM

To compare IBS classification by diary and by child and parent respondents.

METHODS

Children (ages 7-10 years, n = 90) with recurrent abdominal pain and their parents completed IBS symptom questionnaires and 2-week pain and stool diaries. Diaries were coded with two algorithms, one defining stool changes individually and one defining changes normatively. Proportions of dichotomous classifications (IBS vs. not IBS) between pairs of classification methods/respondents were evaluated using Chi-squared tests (χ²) to determine whether coding methods were significantly related, the degree of inclusiveness, and whether differences in classification were randomly distributed.

RESULTS

Individual and normative diary classifications were congruent in 62% of cases, but the individual method classified more children with IBS, 53% vs. 18%. Parent and child questionnaire reports were not correlated. The normative diary classifications and parent questionnaire were the most congruent pair of methods (76% of cases).

CONCLUSIONS

Poor congruence among methods suggests that Rome III IBS criteria need better specification, and efforts to improve parent-child agreement are necessary.

Evaluation of potential factors predicting attainment of full gavage feedings in preterm infants

BACKGROUND

The clinical measures of gastric residuals and abdominal distention are often used to guide feeding in preterm infants, but there are few data demonstrating their usefulness. Similarly, techniques are now available to investigate gastrointestinal (GI) function noninvasively and safely, but their ability to predict attainment of full gavage feedings and/or feeding volume in preterm infants is unclear.

OBJECTIVE

We sought to determine prospectively the potential relationships of attainment of full gavage feedings and feeding volume with clinical measures and noninvasive GI tests.

METHODS

Fifty preterm infants were followed prospectively. Daily tally was taken of gavage feeding intake, gastric residual volumes (GRVs; milliliters per day, number of GRVs >50% of the previous feeding volume, and number of GRVs >2 ml/kg), and abdominal distention. Infants underwent repeated measurement of lactase activity, GI permeability, fecal calprotectin concentration, and gastric emptying.

RESULTS

The number of GRVs >2 ml/kg tended to decrease with postnatal age (p = 0.06). Lactase activity and feeding volume in milliliters per kilogram per day prior to achieving full feedings were correlated (p = 0.007, β = 0.164). There was no correlation between feeding outcomes and GRV (ml/day), GRV >50%, GRV >2 ml/kg, small bowel, colonic, or whole bowel permeability, fecal calprotectin concentration, gastric emptying, or abdominal distention.

CONCLUSIONS

GRV is unreliable in predicting attainment of full gavage feeding. Lactase activity is related to feeding volume. However, other noninvasive GI tests utilized were not predictive. These data cast doubt upon the utility of GRV in guiding feeding therapy. Randomized trials of different GRV management protocols are needed.

A randomized controlled trial of Lactobacillus GG in children with functional abdominal pain

OBJECTIVE

Our aim was to determine whether Lactobacillus rhamnosus GG (LGG) relieves symptoms in children with recurrent abdominal pain.

PATIENTS AND METHODS

A total of 141 children with irritable bowel syndrome (IBS) or functional pain were enrolled in 9 primary care sites and a referral center. Children entered a randomized, double-blind, placebo-controlled trial and received LGG or placebo for 8 weeks and entered follow-up for 8 weeks. The primary outcome was overall pain at the end of the intervention period. At entry and at the end of the trial, children underwent a double-sugar intestinal permeability test.

RESULTS

Compared with baseline, LGG, but not placebo, caused a significant reduction of both frequency (P < .01) and severity (P < .01) of abdominal pain. These differences still were significant at the end of follow-up (P < .02 and P < .001, respectively). At week 12, treatment success was achieved in 48 children in the LGG group compared with 37 children in the placebo group (P < .03); this difference still was present at the end of follow-up (P < .03). At entry, 59% of the children had abnormal results from the intestinal permeability test; LGG, but not placebo, determined a significant decrease in the number of patients with abnormal results from the intestinal permeability testing (P < .03). These effects mainly were in children with IBS.

CONCLUSIONS

LGG significantly reduces the frequency and severity of abdominal pain in children with IBS; this effect is sustained and may be secondary to improvement of the gut barrier.

The association of mast cells and serotonin in children with chronic abdominal pain of unknown etiology

Background

Abdominal pain of unknown origin affects up to 20% of school-aged children. Evaluation of children is symptom-based without clear guidelines to investigate molecular mechanisms of abdominal pain. Aberrant molecular mechanisms may increase intestinal permeability leading to interactions between the immune and nervous systems, subclinical inflammation, and visceral pain. This study evaluated the association between interleukin-6 (IL-6), mast cell infiltrates, and serotonin (5-HT) levels in gastrointestinal (GI) biopsies, with perceived abdominal pain in a pediatric cohort.

Methods

Clinical data and biopsy samples from pediatric patients (n = 48) with chronic abdominal pain, with and without inflammation were included. Formalin-fixed paraffin-embedded GI biopsies were sectioned and immunohistochemistry performed for IL-6 and 5-HT; mast cells were identified with toluidine blue stain. Histological findings were compared to self-reported abdominal pain between groups.

Results

There was significantly greater IL-6 immunoreactivity in biopsies with confirmed histologic inflammation (p = 0.004). There was a greater number of mast cells per HPF in non-inflammatory biopsies (3.5 ± 2.9) compared to the inflammatory biopsies (2.6 ± 1.8) p = 0.049. The non-inflammatory biopsy group was significantly less likely to respond to standard treatment as evidenced by higher pain reports (p = .018). Mast cells (p = .022) and 5-HT (p = .02) were significantly related to abdominal pain scores.

Conclusions

A potential association between self-reported abdominal pain, number of mast cells, and 5-HT levels, which may contribute to perceived GI pain in pediatric patients may exist.

Creation and initial evaluation of a Stool Form Scale for children

OBJECTIVE

To develop a pediatric stool form rating scale and determine its interrater reliability, intrarater reliability, and agreement among pediatric gastroenterologists.

STUDY DESIGN

An ordinal stool scale with 5 categorical stool form types was created on the basis of the Bristol Stool Form Scale, and 32 color 2-dimensional stool photographs were shown to 14 pediatric gastroenterologists. Each gastroenterologist rated the stool form depicted in each photograph with the modified stool scale. Ten gastroenterologists agreed to rerate the stool form depicted in each photograph a minimum of 6 months after the first rating.

RESULTS

A total of 448 ratings were completed; 430 (94%) of all ratings were within at least 1 category type of the most common (modal) rating for each photograph. Eight (25%) stool photographs had complete agreement among all raters. Interrater and intrarater reliability was high with a single measure intraclass correlation of 0.85 (95% confidence interval: 0.78-0.91; P<.001) and 0.87 (95% confidence interval: 0.81-0.92; P<.001), respectively.

CONCLUSION

A modified pediatric Bristol Stool Form Scale provided a high degree of interrater reliability, intrarater reliability, and agreement among pediatric gastroenterologists.

Alterations of the intestinal barrier in patients with autism spectrum disorders and in their first-degree relatives

OBJECTIVES

Intestinal permeability (IPT) was investigated in patients with autism as well as in their first-degree relatives to investigate leaky gut hypothesis. Faecal calprotectin (FC) was also measured in patients with autism, either with or without gastrointestinal symptoms, and in their first-degree relatives.

PATIENTS AND METHODS

IPT results, assessed by means of the lactulose/mannitol test, were compared with adult and child controls and with FC values.

RESULTS

A high percentage of abnormal IPT values were found among patients with autism (36.7%) and their relatives (21.2%) compared with normal subjects (4.8%). Patients with autism on a reported gluten-casein-free diet had significantly lower IPT values compared with those who were on an unrestricted diet and controls. Gastrointestinal symptoms were present in 46.7% of children with autism: constipation (45.5%), diarrhoea (34.1%), and others (alternating diarrhoea/constipation, abdominal pain, etc: 15.9%). FC was elevated in 24.4% of patients with autism and in 11.6% of their relatives; it was not, however, correlated with abnormal IPT values.

CONCLUSIONS

The results obtained support the leaky gut hypothesis and indicate that measuring IPT could help to identify a subgroup of patients with autism who could benefit from a gluten-free diet. The IPT alterations found in first-degree relatives suggest the presence of an intestinal (tight-junction linked) hereditary factor in the families of subjects with autism.

Extracorporeal membrane oxygenation causes loss of intestinal epithelial barrier in the newborn piglet

Extracorporeal membrane oxygenation (ECMO) is an important life-support system used in neonates and young children with intractable cardiorespiratory failure. In this study, we used our porcine neonatal model of venoarterial ECMO to investigate whether ECMO causes gut barrier dysfunction. We subjected 3-wk-old previously healthy piglets to venoarterial ECMO for up to 8 h and evaluated gut mucosal permeability, bacterial translocation, plasma levels of bacterial products, and ultrastructural changes in gut epithelium. We also measured plasma lipopolysaccharide (LPS) levels in a small cohort of human neonates receiving ECMO. In our porcine model, ECMO caused a rapid increase in gut mucosal permeability within the first 2 h of treatment, leading to a 6- to 10-fold rise in circulating bacterial products. These changes in barrier function were associated with cytoskeletal condensation in epithelial cells, which was explained by phosphorylation of a myosin II regulatory light chain. In support of these findings, we also detected elevated plasma LPS levels in human neonates receiving ECMO, indicating a similar loss of gut barrier function in these infants. On the basis of these data, we conclude that ECMO is an independent cause of gut barrier dysfunction and bacterial translocation may be an important contributor to ECMO-related inflammation.

Perturbed zinc homeostasis in rural 3-5-y-old Malawian children is associated with abnormalities in intestinal permeability attributed to tropical enteropathy

Tropical enteropathy and zinc deficiency are major public health problems worldwide. Tropical enteropathy is characterized by reduced mannitol absorption with normal or increased lactulose absorption when a dual sugar absorption test is administered, the results of which are reported as the lactulose:mannitol ratio (L:M). Zinc homeostasis is quantified with a dual stable isotope test. This study tested the hypothesis that endogenous fecal zinc (EFZ) was correlated with the L:M. A dual sugar absorption test and dual stable isotope test were performed on 25 asymptomatic Malawian children aged 3-5 y at risk for tropical enteropathy and zinc deficiency. EFZ and net zinc retention were estimated and correlated with the L:M. Twenty-two children (88%) had an abnormal L:M (L:M>0.10), and the L:M was 0.24+/-0.10 (mean+/-SD). EFZ was 1.68+/-1.06 mg/d, a quantity greater than is seen in healthy populations from the developed world. EFZ was positively correlated with the L:M (r=0.62, p<0.001). Net zinc retention (0.67+/-1.6 mg/d) was negatively correlated with the L:M (r=-0.47, p=0.02). This suggests that perturbed zinc homeostasis is associated with subclinical enteropathy in these children.

Faecal calprotectin concentrations in children with functional gastrointestinal disorders diagnosed according to the Pediatric Rome III criteria

OBJECTIVE

To determine if faecal calprotectin concentrations vary with different entities of functional gastrointestinal disorders (FGID) in children.

METHODS

Children (4-15 years) who were consecutively referred by general practitioners to four general paediatric outpatient clinics for the evaluation of recurrent abdominal pain were assessed according to a research protocol which included clinical examination, a minimum set of blood, urine and stool tests, and clinical reassessment after 6-9 months. The diagnoses of FGID were based on the parent version of the Questionnaire on Pediatric Gastrointestinal Symptoms-Rome III.

RESULTS

Of the 152 patients included, 142 children were diagnosed with FGID. Of these, 126 (89%) provided a stool specimen for quantification of calprotectin. The median calprotectin concentrations were at or lower than 16 mg/kg which was at the lower detection limit and there were no differences between the FGID subgroups. Nine children (7%) had slightly raised values.

CONCLUSION

The faecal calprotectin concentration is within normal limits in FGID and does not vary with different FGID entities suggesting that bowel inflammation is not a significant part of the pathogenesis in FGID.

Effects of timing, sex, and age on site-specific gastrointestinal permeability testing in children and adults

OBJECTIVES

Measurement of gastrointestinal (GI) permeability is commonly used in research and often used clinically. Despite its utility, little is known about sugar excretion timeframes or the potential effects of age and sex on GI permeability testing. We seek to determine the timeframes of sugar excretion and the potential effects of age and sex on urinary recovery of the sugars.

SUBJECTS AND METHODS

Healthy adults (n = 17) and children (n = 15) fasted 4 hours after the evening meal and then ingested a solution of sucrose, lactulose, mannitol, and sucralose. Urine was collected at 30, 60, and 90 minutes after ingestion and then each time the subjects voided during the next 24 hours. Each urine void was collected separately.

RESULTS

Median age for the adults was 47.5 years (range 21-57 years) and for children 10 years (range 5-17 years). There were no differences between children and adults in mean percent dose of sugar recovered. The time of peak urinary recovery of the sugars was generally similar between children and adults. Sucrose urinary recovery declined with age (P = 0.008; r2 = 0.19) unrelated to sex. Lactulose and sucralose urinary recovery declined with age in females (P = 0.05, r2 = 0.24 and P = 0.011, r2 = 0.41; respectively) but not in males.

CONCLUSIONS

Overall, sugar urinary recovery is comparable in children and adults. Specific sugar urinary recovery may change as a function of age and/or sex. These results need to be taken into account when planning and interpreting gastrointestinal permeability studies.

Hypoalgesia related to elevated resting blood pressure is absent in adolescents and young adults with a history of functional abdominal pain

Elevated resting blood pressure (BP) is hypoalgesic in healthy individuals, but this effect is absent in adults with chronic somatic pain. This study tested whether BP-related hypoalgesia is similarly altered in individuals with a history of chronic visceral pain in childhood. Resting BP was assessed in 94 adolescents and young adults with a known history of childhood functional abdominal pain (FAP) and 55 comparable healthy controls. Responses to an acute heat pain stimulus were then evaluated following exposure to two laboratory stressors. A significant participant type x systolic BP (SBP) interaction (p<.005) revealed that elevated resting SBP was associated with significantly higher heat pain threshold (p<.001) in healthy controls, but was unrelated to pain threshold in the FAP group. A similar pattern was observed for heat pain tolerance, with elevated SBP linked to significantly higher pain tolerance (p<.05) in healthy controls, but unrelated to tolerance in the FAP group. Dysfunction in BP-related hypoalgesia associated with FAP was evident regardless of whether childhood FAP had resolved or still persisted at the time of laboratory testing. Subgroup analyses indicated that BP-related hypoalgesia (in healthy controls) and FAP-linked absence of this hypoalgesia was observed only among females. Result suggest that childhood visceral chronic pain may be associated with relatively long-lasting dysfunction in overlapping systems modulating pain and BP that persists even after FAP resolves. Potential implications for later hypertension risk are discussed.

Altered fecal microflora and increased fecal calprotectin in infants with colic

OBJECTIVE

We explored whether gut inflammation, colonic fermentation, and/or an altered colonic flora could provide a pathophysiological mechanism for colic.

STUDY DESIGN

The study population consisted of 36 term infants ranging in age from 14 to 81 days. We measured fecal calprotectin (a marker of neutrophil infiltration) by ELISA; stool microorganisms by denaturing gradient gel electrophoresis, cloning, and sequencing; and breath hydrogen levels using gas chromatography.

RESULTS

During 24 hours, infants with colic (n = 19) cried and fussed for a mean of 314 +/- 36 (SEM) minutes, compared with control infants (n = 17, 103 +/- 17 minutes). Fecal calprotectin levels were 2-fold higher in infants with colic than in control infants (413 +/- 71 vs 197 +/- 46 microg/g, P = .042). Stools of infants with colic had fewer identifiable bands on denaturing gradient gel electrophoresis. Klebsiella species were detected in more colic patients than in control patients (8 vs 1, P = .02), whereas Enterobacter/Pantoea species were detected only in the control patients. These differences could not be attributed to differences in formula versus breast milk feeding, consumption of elemental formula, or exposure to antibiotics.

CONCLUSIONS

Infants with colic, a condition previously believed to be nonorganic in nature, have evidence of intestinal neutrophilic infiltration and a less diverse fecal microflora.

Increased frequency of prediabetes in patients with irritable bowel syndrome

The aim of this study was to compare the occurrence of prediabetes [impaired fasting glucose and/or impaired glucose tolerance are considered to be precursors to type 2 diabetes mellitus (DM)] in irritable bowel syndrome (IBS) cases and matched controls. Ninety-two patients with IBS and 104 healthy matched controls were included in this study. Type 2 DM was considered an exclusion criterion in both groups. Fasting blood glucose, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglyceride levels were examined; after 1 night of fasting, an oral glucose tolerance test with 75 g glucose was administered, and the blood glucose levels after 2 hours were examined. Although there were no significant differences in the triglyceride levels, significant differences were found for total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol levels (P < 0.001, 0.001, and <0.001, respectively). These measures were found to be elevated in the IBS group compared with the control group. The frequency of prediabetes, which is regarded as the first stage of type 2 DM, was also found to be significantly higher in the IBS group (P < 0.001). After adjusting for potential confounders, such as age, lipid levels, and anthropometric measures in the analysis of covariance models, prediabetes was significantly more frequent in the IBS group than in the control group (P < 0.001). Thus, given the higher prediabetes occurrence in IBS, IBS may indirectly indicate a higher risk of DM. Further investigations will be necessary to fully elucidate the mechanisms behind these observations.

A randomized, double-blind, placebo-controlled trial of rifaximin, a nonabsorbable antibiotic, in the treatment of tropical enteropathy

OBJECTIVES

Tropical enteropathy is characterized by an increased urinary lactulose-to-mannitol (L:M) ratio on a site-specific sugar absorption test and is associated with increased intestinal permeability and decreased nutrient absorptive capacity. The etiology of tropical enteropathy is postulated to be intestinal bacterial overgrowth. This study tested the hypothesis that treatment with a nonabsorbable, broad-spectrum antibiotic, rifaximin, reduces the L:M ratio in rural Malawian children, among whom tropical enteropathy is common.

METHODS

All children aged 3-5 years from one village were enrolled in a randomized, double-blind, placebo-controlled trial of treatment with rifaximin for 7 days. The L:M ratio was measured before and after treatment, and the change in the L:M ratio was the primary outcome. Secondary outcomes were changes in the urinary sucrose-to-lactulose (SUC:L) and sucralose-to-lactulose (SCL:L) ratios, as well as changes in the fractions of each test sugar recovered in the urine.

RESULTS

A total of 144 children participated in this study, of whom 76% had an elevated L:M ratio on enrollment (L:M > or = 0.10). Children who received rifaximin did not show an improvement in their L:M ratio compared with those who received placebo (-0.01+/-0.12 vs. 0.02+/-0.16, respectively, P=0.51, mean+/-s.d.), nor were there significant differences between the two groups in excretion of lactulose, mannitol, sucralose, or sucrose, or in the SUC:L and SCL:L ratios.

CONCLUSIONS

Rifaximin had no effect on the tropical enteropathy of 3-5-year-old Malawian children, suggesting that small-bowel bacterial overgrowth is not an important etiological factor in this condition.

Prevalence of small intestinal bacterial overgrowth in children with irritable bowel syndrome: a case-control study

OBJECTIVE

To assess the prevalence of small intestinal bacterial overgrowth (SIBO) in children affected by irritable bowel syndrome (IBS).

STUDY DESIGN

Consecutive children affected by IBS according to Rome II criteria (n = 43) were enrolled at the Gemelli Hospital, Catholic University of Rome. The control population (n = 56) consisted of healthy subjects without IBS symptoms, similar to patients for age, sex, and social background. All subjects underwent lactulose/methane breath test (LBT) to assess small intestinal bacterial overgrowth.

RESULTS

The prevalence of abnormal LBT result was significantly higher in patients with IBS (65%, 28/43) with respect to control subjects (7%, 4/56; OR 3.9, 95% CI 7.3-80.1, P < .00001). Patients with abnormal LBT showed a trend toward a worse visual analog scale score with respect to children with IBS without SIBO, but a significant statistical difference was observed only for bloating.

CONCLUSIONS

Results from this study suggest a significant epidemiologic association between SIBO and IBS in childhood. Placebo-controlled interventional studies with antibiotics used to treat bacterial overgrowth are warranted to clarify the real impact of the disease on IBS symptoms.

Functional gastrointestinal disorders: past and present

BACKGROUND

Chronic abdominal pain is a common complaint in childhood and adolescence. Despite decades of clinical observations and research, it still poses a challenge to pediatric health care professionals. The aim of this review is to highlight the epidemiology of pediatric chronic abdominal pain and to describe the pathogenesis of this disorder, its clinical manifestations, evaluation and therapeutic options.

DATA SOURCES

Articles on chronic abdominal pain in the recent years from PubMed, MEDLINE, and reference textbooks were reviewed.

RESULTS

Chronic abdominal pain, a functional gastrointestinal disorder (FGID), is a multifactorial condition that results from a complex interaction between psychosocial and physiologic factors via the brain-gut axis. A thorough history coupled with a complete physical examination and normal screening studies rule out an organic cause in 95% of the cases. It is highly important for the physician to establish a trusting relationship with the child and parents because successful treatment including modification of physical and psychological stress factors, dietary changes, and drug therapy depends greatly on education, reassurance and active psychological support.

CONCLUSIONS

FGIDs are a cause of great anxiety, distress and morbidity in children as well as adults. As our understanding of these conditions improves, our therapeutic interventions will progress not only to overcome them but also to intervene early in the disease course so as to limit long-term impact.

Alterations in the intestinal microbiota and functional bowel symptoms

Functional gastrointestinal disorders (FGIDs) are highly prevalent in Western countries yet no single mechanism or etiological agent that initiates IBS has been identified. Current research has implicated the intestinal microbiota with FGIDs. This article reviews the available literature/data regarding the intestinal microbiota and FGIDS. The possible relationships between the intestinal microbiota and the intestinal function and functional bowel symptoms are discussed.