Intestinal disease in cystic fibrosis

Status of fluid and electrolyte absorption in cystic fibrosis

Salt and fluid absorption is a shared function of many of the body's epithelia, but its use is highly adapted to the varied physiological roles of epithelia-lined organs. These functions vary from control of hydration of outward-facing epithelial surfaces to conservation and regulation of total body volume. In the most general context, salt and fluid absorption is driven by active Na(+) absorption. Cl(-) is absorbed passively through various available paths in response to the electrical driving force that results from active Na(+) absorption. Absorption of salt creates a concentration gradient that causes water to be absorbed passively, provided the epithelium is water permeable. Key differences notwithstanding, the transport elements used for salt and fluid absorption are broadly similar in diverse epithelia, but the regulation of these elements enables salt absorption to be tailored to very different physiological needs. Here we focus on salt absorption by exocrine glands and airway epithelia. In cystic fibrosis, salt and fluid absorption by gland duct epithelia is effectively prevented by the loss of cystic fibrosis transmembrane conductance regulator (CFTR). In airway epithelia, salt and fluid absorption persists, in the absence of CFTR-mediated Cl(-) secretion. The contrast of these tissue-specific changes in CF tissues is illustrative of how salt and fluid absorption is differentially regulated to accomplish tissue-specific physiological objectives.

Cystic fibrosis and Crohn’s disease: Successful treatment and long term remission with infliximab

The association of cystic fibrosis and Crohn’s disease (CD) is well known, but to date, there are very few cases in the literature of patients suffering from mucoviscidosis who have required treatment with infliximab. We report the case of a 23-year-old patient suffering from cystic fibrosis and severe CD treated successfully with infliximab without any infective complications or worsening of the pulmonary disease and with a long term (2 years) complete remission.

Alpha-AP-2 directs myosin VI-dependent endocytosis of cystic fibrosis transmembrane conductance regulator chloride channels in the intestine

The actin motor myosin VI regulates endocytosis of cystic fibrosis transmembrane conductance regulator (CFTR) in the intestine, but the endocytic adaptor linking CFTR to myosin VI is unknown. Dab2 (Disabled 2) is the binding partner for myosin VI, clathrin, and alpha-AP-2 and directs endocytosis of low density lipoprotein receptor family members by recognizing a phosphotyrosine-binding domain. However, CFTR does not possess a phosphotyrosine-binding domain. We examined whether alpha-AP-2 and/or Dab2 were binding partners for CFTR and the role of myosin VI in localizing endocytic adaptors in the intestine. CFTR co-localized with alpha-AP-2, Dab2, and myosin VI and was identified in a complex with all three endocytic proteins in the intestine. Apical CFTR was increased in the intestines of Dab-2 KO mice, suggesting its involvement in regulating surface CFTR. Glutathione S-transferase pulldown assays revealed binding of CFTR to alpha-AP-2 (but not Dab2) in the intestine, whereas Dab-2 interacted with alpha-AP-2. siRNA silencing of alpha-AP-2 in cells significantly reduced CFTR endocytosis, further supporting alpha-AP-2 as the direct binding partner for CFTR. alpha-AP-2 and Dab2 localized to the terminal web regions of enterocytes, but Dab2 accumulated in this location in Snell's Waltzer myosin VI((sv/sv)) intestine. Ultrastructural examination revealed that the accumulation of Dab2 correlated with prominent involution and the loss of normal positioning of the intermicrovillar membranes that resulted in expansion of the terminal web region in myosin VI((sv/sv)) enterocytes. The findings support alpha-AP-2 in directing myosin VI-dependent endocytosis of CFTR and a requirement for myosin VI in membrane invagination and coated pit formation in enterocytes.

Soft tissue inflammation: presenting feature of Crohn's disease in a cystic fibrosis adolescent

We report Crohn's disease in an adolescent with cystic fibrosis (CF). The patient suffered from recurrent abdominal symptoms, which were attributed to distal intestinal obstruction syndrome (DIOS) until a soft tissue inflammation at the right lumbar region and iliac crest revealed an enterosubcutaneous fistula. The diagnosis of Crohn's disease was confirmed on the basis of radiological, endoscopic and histological findings.

Giant inflammatory polyposis coli as a manifestation of Crohn's disease in patients with coexistent cystic fibrosis

Crohn's disease (CD) arising in children with cystic fibrosis (CF) is well recognized. Indeed, reports suggest that CD is significantly more common in patients with CF than in the general population. Giant inflammatory polyposis is a rare manifestation of idiopathic inflammatory bowel disease and may complicate both ulcerative colitis and CD. Giant inflammatory polyposis has not been specifically reported in patients with coexistent CF and CD. Herein, we report the occurrence of giant inflammatory polyposis in 2 boys attending a tertiary care hospital, with an established diagnosis of CF who subsequently developed CD. Both boys required surgical treatment for CD. In addition to classical features of CD, both colonic resection specimens showed giant inflammatory polyposis. The appearances were modified by the presence of a layer of thick mucus. It is suggested that the coexistence of CF in patients with CD may predispose to the development of giant inflammatory polyposis. In addition to contributing to their development, it also appears that there is a propensity for CF to alter the morphological appearance of giant inflammatory polyposis. This may lead to diagnostic confusion when examining endoscopic biopsies.

Cystic fibrosis: nutritional consequences and management

Malnutrition is an adverse prognostic factor in cystic fibrosis, influencing the course of pulmonary disease and correlating inversely with survival. A positive energy balance between energy intake and the combination of total energy expenditure, energy losses and growth-related energy cost is essential to maintain normal nutritional status. Before starting nutritional supplementation, it is important to rule out pathological conditions that may have a deleterious effect on nutritional status: persistent exocrine pancreatic insufficiency, chronic bacterial pulmonary colonization, impaired glucose tolerance, specific nutritional deficits and associated disorders leading to a decrease of energy intake. Several methods are available, ranging from boosted oral nutrition to behavioural intervention, oral supplementation, enteral nutrition and, rarely, parenteral nutrition. The use of elemental nutrients for either oral supplementation or enteral nutrition seems of no nutritional benefit and is more expensive than conventional polymeric nutrients. Provided that the goals of the nutritional supplementation are fulfilled, simpler is often better.

Gastrointestinal handling of [1-13C]palmitic acid in healthy controls and patients with cystic fibrosis

AIM

To examine the gastrointestinal handling of [1-13C]palmitic acid given as the free acid by measuring the excretion of 13C label in stool in 16 healthy children and 11 patients with cystic fibrosis on their habitual enzyme replacement treatment.

METHODS

After an overnight fast, each child ingested 10 mg/kg body weight [1-13C]palmitic acid with a standardised test meal of low natural 13C abundance. A stool sample was collected before the test and all stools were collected thereafter for a period of up to five days. The total enrichment of 13C in stool and the species bearing the 13C label was measured using isotope ratio mass spectrometry.

RESULTS

The proportion of administered 13C label excreted in stool was 24.0% (range 10.7-64.9%) in healthy children and only 4.4% (range 1.2-11.6%) in cystic fibrosis patients. The enrichment of 13C in stool was primarily restricted to the species consumed by the subjects (that is as palmitic acid).

CONCLUSIONS

There does not appear to be a specific defect in the absorption of [1-13C]palmitic acid in patients with cystic fibrosis. The reasons why cystic fibrosis patients appear to absorb more of this saturated fatty acid than healthy children is not clear and requires further investigation.

Abdominal pain in cystic fibrosis

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Case report: colonic stricture and fibrosis associated with high-strength pancreatic enzymes in a child with cystic fibrosis

High-strength pancreatic enzymes have recently been implicated as a cause of colonic strictures in children with cystic fibrosis (CF). We report a 5-year-old boy with CF who had a stricture of the hepatic flexure region with associated narrowing due to submucosal fibrosis of the transverse colon, secondary to high-lipase pancreatin therapy.

Crohn's disease and cystic fibrosis

Advances in investigative techniques have led to increasing reports of Crohn's disease in CF patients. A retrospective review of the literature on IBD in CF showed findings characterized by ileocolitis with fistula formation; 83% required surgery. A prospective survey of 11,321 CF patients attending 49 CF centers revealed 28 with IBD (25 Crohn's, three ulcerative colitis), ages 4-20 years, mean 15.6 years. The prevalence rate of IBD (247/10(5)) was 7x controls and was accounted for by Crohn's disease (221/10(5)) which was 17x controls. The mechanisms that predispose CF patients to Crohn's disease are discussed.

Gastrointestinal complications in cystic fibrosis

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Pathology mimicking distal intestinal obstruction syndrome in cystic fibrosis

Eight patients with cystic fibrosis had chronic abdominal pain and the other features of distal intestinal obstruction syndrome. Coexistent abdominal pathology was shown in six patients. Two had a small bowel volvulus, and the others had Crohn's disease, a small bowel fistula, appendix abscess, and an ovarian dermoid. Opiate abuse exacerbated symptoms in two other patients.

High dose pancreatic enzymes in cystic fibrosis

Seven patients with cystic fibrosis taking high doses of pancreatin supplements were assessed to determine whether this dose was necessary to achieve adequate fat absorption. Patients reduced their intake from a group mean of 45 to 21 capsules a day. Five patients did not have any significant alteration in fat malabsorption while taking the reduced enzyme dose.