Gastrointestinal peptide profile in children with celiac disease

Fasting Neurotensin Levels in Pediatric Celiac Disease Compared with a Control Cohort

Background and Aims

Neurotensin (NT) is a gut hormone secreted by specific endocrine cells scattered throughout the epithelial layer of the small intestine, which has been identified as an important mediator in several gastrointestinal functions and disease conditions. Its potential involvement in celiac disease (CD) has been investigated, but there are conflicting findings. The aim of this study was to evaluate serum NT levels in children with CD at diagnosis, compared to a control group, and to investigate whether NT correlated in CD patients with symptoms, antibody response, and intestinal mucosal damage. Materials and Methods. Children (1-16 years old) undergoing gastrointestinal endoscopy for CD or for other clinical reasons were included in this study. Patients with CD diagnosed according to the 2012 European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) guidelines without biopsy were also recruited. Fasting serum samples were analyzed for NT levels using ELISA. Logistic regression, Wilcoxon rank sum, and Spearman's rank tests were used for statistical analysis.

Results

Thirty children (18 females, 2.2-15.9 years old) were enrolled. Of 25 patients who underwent endoscopy, 9 were CD patients, 13 were controls, and 3 were excluded due to nonspecific inflammation at duodenal biopsy. CD was diagnosed in 5 patients without biopsy. NT median was higher in CD patients compared to controls (13.25 (IQR 9.4-17.5) pg/ml vs. 7.8 (IQR 7.6-10) pg/ml; p = 0.02). No statistically significant association between NT and clinical, serological, or histological data of CD was observed in this CD cohort.

Conclusions

To our knowledge, this is the first study that evaluates NT in CD children from Italy. Results show that NT is higher in the serum of CD children at diagnosis compared to controls. However, larger-scale studies are required to validate these findings. Whether serum NT levels can be an adjunctive marker for pediatric CD remains currently elusive.

Role of proneurotensin as marker of paediatric coeliac disease

Neurotensin (NT) is a gut hormone functioning proinflammatory through nuclear factor kappa B (NF-κB) and interleukin (IL)-8 secretion or anti-inflammatory through epidermal growth factor receptors. NT mRNA is down-regulated in duodenal biopsies of children with untreated coeliac disease. The aim of this study was to investigate if plasma pro-NT levels correlated with the degree of intestinal mucosal damage and tissue transglutaminase autoantibody (tTGA) levels in children with coeliac disease. Fasting plasma samples from 96 children with coeliac disease and 89 non-coeliac disease controls were analysed for NT precursor fragment pro-NT 1-117 by a chemiluminometric immunoassay. Pro-NT levels were compared with NT mRNA from duodenal biopsies, assessed previously with quantitative polymerase chain reaction (PCR). Illumina core exome arrays were used for human leucocyte antigen (HLA) typing and the Marsh criteria applied to score mucosal damage. Tissue TGA was measured by radio binding assay. A general linear model compared pro-NT levels with diagnosis of coeliac disease, Marsh score and HLA DQ haplotype. Spearman's rank test was used to compare pro-NT levels with tTGA, age and duodenal NT mRNA levels, respectively. Plasma pro-NT levels were elevated in children with coeliac disease (median 23 pmol/l higher, P = 0·003) and in those with severe intestinal mucosal damage (median 24 pmol/l higher for ≥ Marsh 3b versus not, P = 0·0004). Pro-NT levels correlated further with tTGA (r²  = 0·22, P = 0·002), but not with duodenal NTS mRNA levels (r²  = -0·12, P = 0·14). Pro-NT was not associated with any of the HLA risk-haplotypes. Elevated peripheral pro-NT levels reflect more severe forms of active coeliac disease, indicating a potential role of NT in intestinal inflammation.

Motility alterations in celiac disease and non-celiac gluten sensitivity

Regulation of gut motility is complex and involves neuromuscular, immune and environmental mechanisms. It is well established that patients with celiac disease (CD) often display gut dysmotility. Studies have shown the presence of disturbed esophageal motility, altered gastric emptying, and dysmotility of the small intestine, gallbladder and colon in untreated CD. Most of these motor abnormalities resolve after a strict gluten-free diet, suggesting that mechanisms related to the inflammatory condition and disease process are responsible for the motor dysfunction. Motility abnormalities are also a hallmark of functional bowel disorders such as irritable bowel syndrome (IBS), where it has been proposed as underlying mechanism for symptom generation (diarrhea, constipation, bloating). Non-celiac gluten sensitivity (NCGS) is a poorly defined entity, mostly self-diagnosed, that presents clinically with IBS symptoms in the absence of specific celiac markers. Patients with NCGS are believed to react symptomatically to wheat components, and some studies have proposed the presence of low-grade inflammation in these patients. There is little information regarding the functional characterization of these patients before and after a gluten-free diet. A study suggested the presence of altered gastrointestinal transit in NCGS patients who also have a high prevalence of nonspecific anti-gliadin antibodies. Results of an ongoing clinical study in NCGS patients with positive anti-gliadin antibodies before and after a gluten-free diet will be discussed. Elucidating the mechanisms for symptom generation in NCGS patients is important to find new therapeutic alternatives to the burden of imposing a strict gluten-free diet in patients who do not have CD.

Gastrointestinal motility disturbances in celiac disease

It is quite frequent to recognize celiac patients who show gastrointestinal motor abnormalities in clinical practice. In fact, in 30 to 60% of patients, physical examination and dyspeptic symptoms (epigastric discomfort, early satiety) suggest a gastrointestinal motility disorder. Consistent data are now available on the presence of a disturbed motility of the esophagus, stomach, small intestine, gallbladder, and colon of untreated celiac patients. Gastrointestinal abnormalities differ in different gastrointestinal districts. In fact, esophageal transit, gastric and gallbladder emptying, and orocecal transit time are delayed, while colonic transit is faster. These findings are related to the complex interactions among reduced absorption of food constituent (in particular, fat), neurologic alteration, and hormonal derangement. Motility disorders of the gut are also a predisposing factor in the development of small intestinal bacterial overgrowth and may contribute both to development of symptoms in some untreated celiacs and to the persistence of symptoms after gluten-free diet in some of them. All these alterations fortunately disappear after gluten-free diet, and patients return to well being status. Whatever the initial event in the pathogenesis of the celiac lesions may be, we know for certain at this time that gastrointestinal disturbances play an important role in the genesis of gastrointestinal symptoms in celiac disease and that surveillance for celiac disease in patients complaining of dysmotility-like dyspeptic symptoms should be increased.

Low fecal elastase: potentially related to transient small bowel damage resulting from enteric pathogens

Fecal elastase is considered to be a highly sensitive and specific non-invasive exocrine pancreatic function test. However, enteropathy may theoretically cause decreased exocrine pancreatic enzyme secretion through alteration of enteric hormone release.

OBJECTIVE

The aim of this study was to evaluate the possible influence of transient small bowel damage on pancreatic elastase secretion.

METHODS

We studied 166 children (aged 4 months to 14 years, mean 2 years); 114 of these children had acute enteritis and 52 children were control subjects (with gastro-intestinal symptoms or extra-intestinal diseases). Feces were collected from each patient 3 days after the onset of diarrhea and then tested for fecal elastase, bacterial pathogens, Rotavirus, and Adenovirus. Liquid fecal samples were not considered eligible for elastase measurement. Pancreatic elastase was measured using an ELISA method (Sche.Bo.Tech, Germany). We classified the results, expressed in microg/g stool, as: severe pancreatic insufficiency (<100 microg/g), moderate pancreatic insufficiency (100 to 200 microg/g), and normal (>200 microg/g).

RESULTS

In the acute enteritis group we found severe levels in 14 (12%) children, moderate levels in 18 children (16%), and normal levels in 82 children (72%). In contrast, 52 of 52 (100%) control subjects demonstrated normal results. Statistical analysis (Wilcoxon rank test) demonstrated a significant difference between the enteritis and control groups (P < 0.01). Serial measurement of fecal elastase performed in 10 patients with enteritis showed a progressive increase of levels in 6 patients and an early decline with subsequent increases in the other 4 patients.

CONCLUSIONS

Transient exocrine pancreatic insufficiency may be present in transient small bowel disease, caused by both bacterial and viral infections, possibly related to reduced enteric CCK secretion.

Gallbladder emptying and somatostatin and cholecystokinin plasma levels in celiac disease

OBJECTIVE

Gallbladder hypomotility in celiac disease has been attributed to decreased cholecystokinin secretion. The possible influence of somatostatin, which inhibits gallbladder motility, however, has never been evaluated. In this study gallbladder emptying and cholecystokinin and somatostatin plasma levels were evaluated in response to a fatty meal in patients with celiac disease at diagnosis and after long-term gluten-free diet and in controls.

METHODS

Gallbladder volume and plasma levels of cholecystokinin and somatostatin were measured by ultrasonography and radioimmunoassay, respectively, at 0 time and 30, 60, 75, and 90 min after an oral fatty meal (227 kcal, 45% fat) in 10 celiac patients at diagnosis and after 18 months of successful gluten-free diet and in 10 healthy subjects. The pattern of gallbladder emptying was evaluated by mixed factorial analysis of variance and the curve fitting by multiple regression analysis.

RESULTS

Patients at diagnosis had significantly greater fasting gallbladder volume and higher somatostatin plasma levels than controls (25.7 +/- SD 9.7 ml vs 16.8 +/- 7.0 ml, p = 0.021 and 9.3 +/- 4.6 vs 4.8 +/- 3.4 pmol/L, p = 0.023, respectively), significantly lower fatty meal-induced gallbladder ejection fraction (55 +/- 11.2% vs 76 +/- 7.2%, p = 0.005), and cholecystokinin peak and smaller area under the cholecystokinin secretion curve (3.1 +/- 2.3 pmol/L vs 10.5 +/- 6.9 pmol/L, p = 0.028 and 157 +/- 142 pmol/L/90 min vs 453 +/- 229 pmol/L/90 min, p = 0.028, respectively). The two groups had a similar emptying pattern (p = 0.8913) expressed by a significant quadratic term of the emptying function (p = 0.0001). The mean overall emptying volume was significantly greater in patients than in controls (p = 0.0007). Gluten-free diet normalized these findings.

CONCLUSIONS

In patients at diagnosis, elevated somatostatin levels were associated with increased gallbladder fasting volume, whereas decreased cholecystokinin secretion was responsible for the reduced gallbladder emptying. Gluten-free diet reversed these abnormalities.

Influence of jejunal morphology changes on exocrine pancreatic function in celiac disease

BACKGROUND

Concurrent exocrine pancreatic dysfunction may be one of the factors implicated in malabsorption in untreated celiac disease, as shown by studies on bicarbonate and pancreatic enzyme secretion. The purpose of this study was to evaluate exocrine pancreatic function in relation to jejunal morphology in celiac disease.

METHODS

Thirty-six patients fulfilling the ESPGHAN criteria for celiac disease, aged 3 to 18 years and 36 control subjects matched for age and sex were investigated. The design of the study included measurement of serum pancreatic isoamylase by a chromogenic method after selective inhibition of sialic isoamylase in the untreated phase in patients consuming a gluten-containing diet and after gluten elimination for a period of 1 year; fecal human elastase activity determined by enzyme-linked immunosorbent assay in patients consuming a gluten-free diet and again after gluten challenge for 6 months; correlation of serum pancreatic isoamylase and fecal elastase to the jejunal morphology, classified by criteria described by Marsch; the enzymes in the control group; and ultrasonography of the pancreas in both groups.

RESULTS

Enzyme values obtained from celiac disease patients with normal mucosa were significantly higher than those obtained from patients with villous atrophy (p < 0.001) and comparable to those obtained from the control group. Serum pancreatic isoamylase activity increased to normal after gluten elimination, and human elastase activity decreased to values below 200 microg/g of stool after gluten challenge. Enzyme activity was related inversely to the degree of intestinal damage. The echogenicity of the pancreas was normal, regardless of enzyme activity or gut morphology.

CONCLUSIONS

Exocrine pancreatic function is abnormal in celiac disease when mucosal atrophy is present. Exocrine pancreatic function parameters are associated with the changes of intestinal mucosal morphology in three consecutive phases of the disease.

Circulating oxyntomodulin-like immunoreactivity in healthy children and children with celiac disease

BACKGROUND

The aim of the study was to evaluate the new hormonal entity oxyntomodulin-like immunoreactivity in malabsorption states, and to assess its potential in celiac disease management.

METHODS

We measured basal and postprandial oxyntomodulin-like immunoreactivity values in 35 children divided into 3 groups: group 1 was composed of 13 children with celiac disease, either under a gluten-free diet (8 patients) or normal diet (5 patients); group 2 was composed of 8 children hospitalized for gastroenteritis or chronic diarrhea, without biological evidence of malabsorption nor abnormal jejunal mucosa; group 3 was composed of 22 control subjects.

RESULTS

Fasting and meal-stimulated levels in the control group were 71+/-10 and 130+/-26 pmol/l, respectively. Mean concentrations were elevated in patients with celiac disease (basal = 349+/-254 pmol/l, postprandial = 446+/-332 pmol/l) and in the group 2 (basal = 139+/-58 pmol/l, postprandial = 218+/-85 pmol/l), but the difference with control subjects did not reach statistical significance. In children with celiac disease, basal and stimulated values correlated with the degree of malabsorption as assessed by hemoglobin (p = 0.006 and p = 0.01, respectively) and serum folate concentrations (p = 0.03 and p = 0.02, respectively).

CONCLUSIONS

Oxyntomodulin-like immunoreactivity is noticeably higher in healthy children than previously measured in healthy adult subjects. This hormonal parameter is not an adequate diagnostic tool in celiac disease. Nevertheless, in the context of celiac disease, its elevation reflects the degree of malabsorption and may provide a quantitative approach of the extent of mucosal damage.

Neuropeptide Y (NPY) enhances proliferation of human colonic lamina propria lymphocytes

Neuropeptide Y (NPY) is one member of a family of peptides with a wide range of physiological effects on the CNS, cardiovascular, and respiratory systems. NPY is widely distributed throughout the peripheral and central nervous systems. It has also been found within the colon, liver and gallbladder in close anatomic proximity to the mucosal immune system. In this study, we investigated the effect of NPY on human gut mucosal immune function. We examined colonic lamina propria lymphocyte (LPL) proliferation by measuring DNA synthesis, ornithine decarboxylase (ODC) activity, and polyamine biosynthesis. NPY enhanced ODC activity and polyamine biosynthesis in Con A-stimulated LPL, and enhanced thymidine incorporation into Con A-stimulated LPL but not into monocyte-depleted LPL. Moreover, exogenous IL1-beta partially restored NPY's stimulatory effect on monocyte-depleted LPL DNA synthesis. Our results demonstrate that NPY enhances human colonic LPL proliferation and that this effect is partially IL1-beta dependent. Our data also suggest that NPY's effect may be mediated via polyamine biosynthesis. We postulate that the NPY may have an important impact on human mucosal immune function.

Gut hormones and gastrointestinal motility in children with cystic fibrosis

Intestinal dysmotility may be an important factor contributing to various gastrointestinal complications associated with cystic fibrosis. Motilin, enteroglucagon, neurotensin, and peptide YY may each play a role as endocrine hormones influencing gastrointestinal motor activity. Fasting children with cystic fibrosis (N = 8) and controls (N = 18) received a liquid nutrient test meal (fat 4 g/100 ml, protein 4 g/100 ml, carbohydrate 20 g/100 ml, 125 kcal/100 ml; 200 ml/m2) containing lactulose (5 g/100 ml), and the plasma concentrations of these peptides were studied. Mouth-to-cecum transit time was simultaneously studied using the breath H2 technique. Fasting levels of peptide YY and the postprandial response of all four peptides were significantly increased in those with cystic fibrosis. In repeat studies on those with cystic fibrosis after a period of altered pancreatic enzyme supplementation, no significant changes in peptide concentrations were observed. A rise in breath H2 permitting estimation of mouth-to-cecum transit time was noted in 17 control subjects (70-220 min, median 140). In contrast, a rise occurred in only two with cystic fibrosis after low-dose enzyme (70 and 180 min), and four after high-dose enzyme replacement (120-230 min, median 155). Altered gut hormone secretion may play a role in the pathophysiology of intestinal dysmotility in patients with cystic fibrosis.

Plasma precursor amino acids of central nervous system monoamines in children with coeliac disease

Some children with coeliac disease show behavioural disorders such as depression and other signs which have been correlated with reduced central monoamine metabolism. We have therefore investigated the brain availability of the monoamine precursors tryptophan and tyrosine in 15 untreated children with coeliac disease and 12 treated children with coeliac disease as well as in 12 control children. Significantly decreased plasma concentrations of tryptophan were found in untreated children (mean (SD) 13 (4) mumols/l, p less than 0.001) compared with treated children (31 (13) mumols/l), and in both groups of coeliac children when compared with control children (81 (22) mumols/l). A significantly lower ratio of plasma tryptophan to large neutral amino acids (tyrosine, valine, isoleucine, leucine, and phenylalanine) was also observed, which could indicate impaired brain availability of tryptophan in coeliac children and was more pronounced in untreated children. The impaired availability of tryptophan could produce decreased central serotonin synthesis and in turn behaviour disorders in children with coeliac disease.